This invention pertains generally to valves for controlling fluid flow and particularly to microvalves that use electrokinetic pump actuation for fluid flow control in microfluidic systems.
Recent advances in device miniaturization have led to the development of microfluidic devices that are designed, in part, to perform a multitude of chemical and physical process. Typical applications include analytical and medical instrumentation, and industrial process control equipment. Microvalves are an important component of the microfluidic systems used in these applications.
Although there are numerous micro-fabricated valve designs that use a wide variety of actuation mechanisms, only two of these designs are incorporated in commercially available microvalves, with thermopneumatic expansion being used as the actuation mechanism in one design and a shape memory alloy diaphragm and bias spring in the other. However, these microvalves suffer from the fact that they consume relatively large amounts of power during operation, typically between 200 and 1500 mW depending upon the design. This high power consumption can be a significant disadvantage if power must be supplied by batteries or the microvalve is placed on a microchip. Moreover, valves using the aforementioned actuation mechanisms can only generate modest actuation pressures.
What is needed is a microvalve that can be used for microfluidic systems that requires significantly less power to operate, can exert larger actuation pressures than can be presently developed by conventional microvalves, is suitable for use on a microchip, and provides both rapid "on" and "off" actuation.